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Baduini, C.L. 1997. Spatial and temporal patterns of zooplankton biomass in Monterey Bay, California during the 1991-1993 El Niņo and an assessment of the sampling design. California Cooperative Fisheries Investigations (CalCOFI) Rep 38: 193-198. Full Article

To estimate spatial and temporal zooplankton biomass, and the appropriateness of the sampling design, eighteen surveys were conducted in Monterey Bay, California, between November 1991 and August 1993. Vertical tows were taken to estimate zooplankton bioinass in six regions of the bay on each survey day. In year 1, when 100-m vertical tows were made, zooplankton biomass peaked in January, March, and August; in year 2, when 50-ni vertical tows were made, biomass peaked in April, August, and October. Mean zooplankton biomass differed significantly among seasons for both years, but trends differed between years. In year 1, mean biomass measured in the Davidson and oceanic seasons was significantly greater than in the upwelling season. In year 2, mean biomass measured in the upwelling and oceanic seasons was significantly greater than in the Davidson period. The seasonal trends in zooplankton biomass during this study were representative of similar trends for the phytoplankton cycle in Monterey Bay, which had a spring and an autumn bloom and decreased biomass in winter. Low zooplankton levels recorded in Monterey Bay during February and April 1992 and January and March 1993 were probably related to an El Niiio- Southern Oscillation warm-water event (ENSO) in 1991-93. The sampling regime adequately revealed large-scale spatial (tens of km) and temporal (seasonal) differences in zooplankton biomass, but probably does not adequately describe smaller spatial and shorter temporal processes.

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